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Any how, interesting observations Meal. and yes, cranking test for starting batteries is an important indicator. But cranking test for traction batteries is not practical, traction batteries should provide deep discharge (till 10.5 V) but can not deliver high power for starting an engine unless you over rate it, over rating is more money, weight and size.
Sciencisto, maybe building your own battery is fine, but I think it may cost more than buying a new one, after all, ready made ones are mass production and should cost less.
You said that charging lead acid batteries should be only with a pulsed charger, I dont know about that, car charging alternator is not pulsed, yet, with proper usage, good batteries may last for long worth their price. I agree that pulsed charging is good for batteries every now and then, but as soon as you get rid of sulfate, what good would it be for the battery?
Statistics: Posted by Amr — Fri Dec 10, 2010 8:29 am
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And remember one basic thing -- lead acid batteries are to be charged with PULSED current only, NEVER ever with direct current or they will be destroyed soon.
Statistics: Posted by sciencisto — Sun Nov 28, 2010 5:16 am
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AUTOPSY OF LARGE M/CYCLE BATTERY
First I emptied the acid.
I cut open the case. I did it with a 'box-cutter.' I held a very small butane torch in my left hand and trained the flame on the blade which was in my right.
I cut open all around the top of the battery in a band. The band was from the top part of the battery case to the top of the plate assemblies.
I wanted to see if the 'combs' which the plates attach to were broken. On a superficial examination it seemed all the plates were attached to at least the top of the plates.
I cut one of the end cell's plastic casing off so I could expose all the plates in that cell. I noticed that all the negative plates were well-fixed. But this wasn't surprising as they are made of solid lead. - but the positive plates were rotten.
The positive plates are lead 'paste' on a lead lattice/grid. Every positive plate was attached to the above 'comb' by the top horizontal piece of the grid. But the lines of lead which lead down into the plates from there were mostly disconnected.
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By prying off the solid neg plates I exposed the positive plates. Without exception the positive plates were just lead-powder sandwiched between the negative plates, and were only held in place because they were pressed in by the insulators and the neg plates.
For example:- The top of the grid of the pos plate has five pieces leading downwards - in a good battery. But with these only two might have been connected.
So the reason this battery failed was the degradation and degeneration of the positive grids.
With this battery, only a portion of the grid was intact. So basically the battery lost cranking power and capacity because it was effectively a smaller battery by virtue of the fact that the active plates were smaller.
* This battery had some crud in the top. Perhaps some of it could have shorted some plates in some cells. This crud seemed to come from the connecting inter-cell bars. It was flakey.
* The electrolyte was fairly cloudy. This might be a clear indication of the positive plates turning to mush.
* The plate assemblies were a tight fit. Not unduly distended. I couldn't see much chance for any crud on the top of the plates being able to find their way to the well at the bottom.
Interesting! I want to find a reliable way of testing the integrity of the positive grid ... Oh! I know! A cranking test!
I can't see a way to fix such a problem. - Clearly a battery made with solid plates will last longer than a starter battery! They're CRAP!
Statistics: Posted by mael — Sat Nov 27, 2010 4:28 pm
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